TV is My Parent

Sia's latest release is a concert DVD called TV is My Parent, which includes a set from her concert at the Hiro Ballroom in New York, four music videos, and traditional "behind the scenes with the band" footage. While I'm a big fan of Sia's quirky avant-garde pop, a concert DVD isn't usually something I would pick up. If I already have the music on CD, why do I need lower quality versions punctuated with inaudible on-stage banter?